Table 2. Experimental and calculated energies levels (cm⁻¹) of Cr³⁺ ion in octahedral symmetry in Gd_0.99Er_0.01Al_0.995Cr_0.05O₃ nanoparticles.

Oh	E obs	[this work]	[this work]
4A2g(4F)	0	0	0
2Eg(2G)	13 774	13 772	13 902 (4)
2T1g(2G)		14 312	14 434 (4)
			14 493 (2)
4T2g(4F)	17 760	17 760	17 666 (2)
			17 722 (4)
			17 832 (2)
			17 836 (4)
2T2g(2G)	—	20 906	20 974 (4)
			21 083 (2)
4T1g(4F)		24 276	24 165 (4)
			24 173 (2)
			24 185 (4)
			24 187(2)
2A1g(2G)	—	29 324	29 507 (2)
2T1g(2P)	—	31 382	31 582 (2)
			31 629 (4)
2T1g(2H)	—	31 712	31 803 (2)
			31 978 (4)
2Eg(2H)	—	33 325	33 458 (2)
2T1g(2H)	—	36 266	36 324 (2)
			36 360 (4)
4T1g(4P)	—	38 528	38 388 (2)
			38 403 (4)
			38 503 (4)
			38 535 (2)
2T2g(2H)	—	40 671	40 574 (2)
			40 674(4)
2A2g(2F)	—	42 024	42 033 (2)
2T2g(2aD)	—	49 088	49 341 (2)
			49 451 (4)
2T2g(2F)	—	50 505	50 543 (2)
			50 652 (4)
2Eg(2aD)	—	50 661	50 662(4)
2T1g(2F)	—	55 225	55 122 (2)
			55 246 (4)
2T2g(2bD)	—	69 140	69 008 (4)
			69 204(2)
2Eg(2bD)	—	72 823	72 879 (4)